Auditory Tracts

Question 1

Where are cell bodies of the auditory pathways found?

Answer 1

Spiral ganglion

Question 2

Where do the nerves of the auditory pathways enter the brainstem?

Answer 2

Pontomedullary junction

Question 3

Where do the nerves of the auditory pathways synapse?

Answer 3

Cochlear nuclei

Question 4

What are the different cochlear nuclei?

Answer 4

Dorsal cochlear and ventral cochlear (subdivided into anterior/posterior divisions)

Question 5

What information do monaural tracts transmit? Where does this information go?

Answer 5

Information about sounds at a single ear; routed to contralateral side

Question 6

What information do binaural tracts transmit? Where does this information go?

Answer 6

Information about differences between sounds at both ears; handled by central pathways that receive, compare, and transmit this input

Question 7

What is conduction deafness?

Answer 7

Deficit related to an obstructed, or altered, transformation of sound to the tympanic membrane or through ossicle chain

Question 8

What is sensorineural (nerve) deafness?

Answer 8

Results from damage to the cochlea, the cochlear part of CN VIII or to the cochlear nuclei

Question 9

What is central deafness?

Answer 9

Damage to the central pathways

Question 10

What is the origin of blood supply to the cochlea and auditory nuclei of the pons and medulla?

Answer 10

Basilar artery

Question 11

What supplies the inner ear and the cochlear nuclei?

Answer 11

Internal auditory (labyrinthine) artery, usually a branch of AICA

Question 12

What will occlusion of the AICA result in?

Answer 12

Monaural hearing loss; may also damage the emerging fibers of the facial nerve and the pontine gaze center, resulting in monaural deafness combined with ipsilateral facial paralysis and an inability to look toward the side of the lesion

Question 13

What supplies the superior olivary complex and lateral lemniscus?

Answer 13

Short circumferential branches of the basilar

Question 14

What supplies the inferior coliculus?

Answer 14

Superior cerebellar and quadrigeminal arteries

Question 15

What supplies the medial geniculate bodies?

Answer 15

Thalamogeniculate arteries

Question 16

What supplies the primary auditory and association cortices?

Answer 16

M2 segment of the middle cerebral artery

Question 17

What is the function of Wernicke’s area?

Answer 17

Comprehension of spoken language

Question 18

What is the function of Broca’s area?

Answer 18

Instruction for language output, planning movements to produce speech, and providing grammatical function of words

Question 19

What is the dominant hemisphere?

Answer 19

Left hemisphere in 94% of adults

Question 20

In the right hemisphere, what is the function of the area analogous to Wernicke’s area?

Answer 20

Interpreting nonverbal signals from other people

Question 21

In the right hemisphere, what is the function of the area analogous to Broca’s area?

Answer 21

Instructions for producing non-verbal communication including emotional gestures and intonation of speech

Question 22

What is agnosia? What is auditory agnosia?

Answer 22

Agnosia: inability to identify an object despite being able to perceive it

Auditory Agnosia: inability to describe a sound that has been heard

Lesion is unimodal sensory association cortex bilaterally

Question 23

What does a lesion in Wernicke’s area cause?

Answer 23

Wernicke’s aphasia (receptive or fluent); defect of the comprehension of language, but expression is fine

Also unable to understand what is said to them, unable to read (alexia), unable to write comprehensible language (agraphia), or display fluent paraphasic speech

Question 24

What does a lesion in Broca’s area cause?

Answer 24

Broca’s aphasia (expressive aphasia or non-fluent aphasia); loss of the ability to speak fluently, but can understand spoken and written language

Severe: results in inability to speak (mutism)

Minor: limited speech, short habitual phrases (hi, yes, no); speech is slow, labored, poor enunciation; nonessential words are omitted

Question 25

What is a global lesion?

Answer 25

Type of non-fluent aphasia; lesion of lateral sulcus; receptive and expressive deficits, reading and writing impaired

Question 26

What is conduction aphasia?

Answer 26

Type of fluent aphasia; lesion of supramarginal gyrus and arcuate fasciculus; can’t repeat, intact fluency, good comprehension, speech interrupted by word-finding difficulties; reading intact, writing impaired

Question 27

What is a transcortical motor lesion?

Answer 27

Nonfluent type; grammar preserved, comprehension is normal, naming and repetition is preserved; occurs at ACA-MCA border zone

Question 28

What is a transcortical sensory lesion?

Answer 28

Fluent type; grammar is preserved, comprehension and naming is impaired, repetition is preserved; occurs at MCA-PCA border zone